Laser shock peening method for improving intensity of laser induced shock wave by adopting time sequence double laser pulse

Abstract

The invention discloses a laser shock peening method for improving the intensity of a laser induced shock wave by adopting a time sequence double laser pulse, and belongs to the field of laser processing. The laser shock peening method aims at solving the problem that existing laser shock peening systems are generally insufficient in laser energy utilization so as to affect the intensity of shockwaves. The method comprises the step that a laser pulse A and a laser pulse B sequentially irradiate and shock the same position of a workpiece surface in a relative delay mode. The specific process comprises the following steps that firstly, the pulse A irradiates and shocks the surface of the workpiece to form an initial plasma, when the electron density of the initial plasma is reduced to be below the critical density of forming the plasma shielding effect, the pulse B which reaches in delay irradiates and shocks a target area, and a part of the laser energy of the pulse B reaches the surface of an absorption layer so as to continue to gasify and ionize the material of the workpiece; and the other part of the laser energy of the pulse B is subjected to inverse bremsstrahlung absorptionby the initial plasma formed through the pulse A. Under the conditions that the output capability of a laser device is not increased and the irradiation area of a light spot is not changed, the purpose of improving the intensity of the shock wave is achieved.

Description

technical field

[0001] The invention belongs to the field of laser processing, and relates to a laser shock strengthening technology for the surface of metals, ceramics and other materials, and in particular to a method without amplifying the output capability of a laser device (laser pulse energy) and without changing the size of the irradiation spot on the surface of a workpiece. , a technical method to increase the shock wave intensity by constructing time-sequenced double laser pulses to irradiate and impact the workpiece one after another. Background technique

[0002] Laser shock strengthening is a new type of material surface strengthening technology. Its principle is: using short pulses (a few nanoseconds to tens of nanoseconds), high peak power density (greater than GW / cm 2 ) laser beam irradiates the surface of a metal or ceramic workpiece, so that the absorbing protective layer coated on the surface of the workpiece absorbs the laser energy and undergoes explosive...

Images